In recent years, there has been a large increase in the capacity of storage apparatuses, which are now commonly equipped with multiple storage devices. In keeping with the diversity of user needs regarding cost and performance, storage apparatuses may include different types of storage devices, such as Hard Disk Drives (HDDs) and Solid State Drives (SSDs), and the storage capacity and access speed may differ even for the same storage devices.
There is also a tendency for storage apparatuses to use a greater variety of storage devices for expansion and maintenance reasons. To facilitate expansion, some storage apparatuses are provided with one or more drive enclosures that can house a plurality of storage devices.
To protect data from storage device failures, storage apparatuses use a technology called Redundant Arrays of Inexpensive Disks (RAID). To set up a RAID in a storage apparatus, storage devices are selected to construct the RAID. A setting operation is then performed manually or automatically.
See, for example, the following documents:
Japanese Laid-open Patent Publication No. 2000-20245
Japanese Laid-open Patent Publication No. 09-6547
U.S. Pat. No. 8,782,342
However, when a larger number and greater variety of storage devices are connected to a storage apparatus, there is an increase in complexity and it becomes difficult to select the storage devices to construct a RAID. When selecting the storage devices to construct a RAID, it is favorable to consider the possibility of failures occurring not only for individual storage devices but also for drive enclosures that house a plurality of storage devices.